GnuCash allows you to track bank accounts, stocks, income, and expenses. As quick and intuitive to use as a checkbook register, it is based on professional accounting principles to ensure balanced books and accurate reports. It is backed by an active development community and is blossoming into a full-fledged accounting system.

Tiny ERP is a complete ERP and CRM. The main features are accounting (analytic and financial), production management (MRP), stock management, sales and purchases management, task automation, marketing campaigns, help desk, POS, etc. Technical features include a distributed server, flexible workflows, an object database, a dynamic GUI, an XML-RPC interface, and customizable reports.

beancounter enables stockmarket data analysis and performance evaluation. It has two main modes. The first is data gathering - both current data (e.g. closing prices, high, low, volume etc.) and historical price data can be retrieved efficiently using multiple securities per requests, and stored in an SQL database (PostgreSQL, MySQL, and SQLite are supported) via easy command line operations. The second mode is data analysis, based on the previously stored data. This comprises various performance reports, as well as a Value-at-Risk analysis. beancounter is implemented as a Perl module, and a Perl command-line frontend to the module. It supports different stock markets from around the globe, foreign exchange rates, US mutual funds, and US options.

Fairmat is a derivative and capital investments modelling tool. It permits you to build a pricing model for many financial projects (or derivative contracts) using a graphical representation blended with a high level algebraic language. It is also possible to use it to evaluate projects and perform real options valuations. The platform can be extended using a plug-in system.

QuantLib is a cross-platform, quantitative finance
C++ library for modeling, pricing, trading, and
risk management in real-life. It is also wrapped
as Python/Ruby/Scheme modules. Extensions for
Excel, R, and Mathematica are available. Other
such extensions are under consideration. QuantLib
offers tools that are useful both for practical
implementation and for advanced modeling. It
features market conventions, yield curve models,
solvers, PDEs, Monte Carlo (low-discrepancy
included), exotic options, VAR, and so on.

Finance::Quote is a Perl module which can fetch on-line stock quotes, including those from American, European, Canadian and Australian markets. Information from a number of investment houses is also available. Features include currency lookups and conversions, automatic failover support, and loadable user modules.